In a mobile communications system, a beam tilt (generally referred to as a downtilt of a beam, a downtilt for short) of an antenna is adjusted to adjust an area covered by a mobile communications signal. The beam tilt of the antenna is adjusted by adjusting a phase shifter inside the antenna. In this way, a signal phase of each unit inside the antenna changes, thereby changing the beam tilt.
With limitation on a site resource of a mobile base station, a multi-band antenna is increasingly demanded. Currently, the multi-band antenna is already a mainstream application. Because of strength of a mechanical part (such as a pole or a tower) bearing the multi-band antenna, a structure size, especially a length and a width of the antenna needs to be as small as possible, to reduce wind load and weight. Therefore, smaller space occupied by a downtilt adjustment apparatus disposed inside the multi-band antenna is more conducive to reducing a size of the multi-band antenna.
Currently, a mainstream downtilt adjustment apparatus is transmitted and connected by using a rigid mechanical part, and cannot be flexibly disposed inside the antenna. In addition, because of a plurality of times of transfer connections and connections, the mainstream downtilt adjustment apparatus occupies large space inside the antenna, and has low transmission efficiency.